How Can I Securely Download Sensitive Documents While Preventing Unauthorized Access?

Securing Downloads for Sensitive Documents

You aim to safeguard a folder named "docs" containing highly confidential documents available for download by authorized users. To achieve this, you've implemented security measures such as .htaccess protection, user redirection during download to obscure the folder path, and enforced validation and sanitization of input.

Additional Security Recommendations:

• Store Files Outside the Webroot: Move the sensitive files to a directory outside the web document root, preventing direct access via URLs.
• PHP Script for File Delivery: Create a PHP script that receives the file download request and verifies the user's authorization before transmitting the file. This ensures that the user cannot simply click on the file's URL and bypass security controls.

• Example PHP Script:

  <?php
    if (!isset($_SESSION['authenticated'])) {
        exit;
    }
    $file = '/path/to/file/outside/www/secret.pdf';
  
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename=' . basename($file));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    ob_clean();
    flush();
    readfile($file);
    exit;
  ?>

• Limit Direct File Access: Add a conditional statement to your .htaccess file that restricts direct access to files in the "docs" folder.
• Disable Directory Listing: Ensure that directory listing is turned off to prevent users from browsing the directory contents, even if they can guess the URL.
• Implement Cross-Site Request Forgery (CSRF) Mitigation: Employ CSRF protection to prevent malicious scripts from tricking users into performing unauthorized file downloads.
• Monitor Access Logs: Regularly review your access logs to identify any suspicious activity or failed login attempts.

By implementing these recommendations in conjunction with your existing security measures, you can effectively protect your sensitive documents from unauthorized access while enabling secure downloads for authorized users.

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